1. Field of Invention
This invention relates to joist hangers.
2. Prior Art
The value of using joist hangers for reinforcement of intersecting framing members has been recognized and accepted for more than 100 years. New building materials are continually being developed and construction methods are likewise adapted to conform to resultant updates in building codes. A relevant adaptation to modern construction methods is the evolution of the joist hanger. Joist hangers are mass-produced, relatively inexpensive, and provide strength for holding framing members together. Joist hangers are made for very narrow and specific applications as the following example illustrates:
Laminated Veneer Lumber, commonly known as LVL, is one type of framing member that was developed as a stronger and more reliable alternative to lumber sawn from trees. LVL is widely used in building construction throughout the world. The term ‘LVL’ represents any laminated type beam.
The standard width of LVL members is nominally larger than the standard width of tree-sawn lumber. Because of this difference in width, joist hangers manufactured for tree-sawn lumber are not compatible with LVL. The industry responded by providing new joist hanger sizes to accommodate LVL. To further illustrate, joist hangers are mass-produced to accommodate singles or multiples of tree-sawn members of the same width. Similarly, joist hangers are also mass-produced to accommodate singles or multiples of LVL members of the same width. Consequently, joist hangers for tree-sawn lumber, whether singles or multiples, are not interchangeable with joist hangers for LVL and vice versa. As a disadvantage, neither LVL joist hangers nor joist hangers made for tree-sawn lumber are designed to be modified for use beyond that for which they were specifically designed.
The art of building construction sometimes presents problems for which currently available solutions are not cost effective or not efficient or both. One such problem occurs when a joist requires a joist hanger but for a variety of reasons the width of the joist does not conform to standard sizing. Mass-produced joist hangers are designed to fit standard and very specific joist sizes. It is neither practical nor cost effective to produce, joist hangers of an unknown number of in between sizes and therefore in-between size joist hangers are not commercially available.
Modern framing members are available in different types and sizes. These different members are commonly used within a single structure. There are situations where these dissimilar framing members are of necessity used in combination with each other resulting in a finished member that does not conform to standard sizing with regard to commonly available joist hangers. Thus, in-between sized joist hangers are sometimes required however applicant knows of no available product to fill this need.
Other situations are possible that result in the same problem. Framers sometimes introduce various adaptations such as sandwiching a piece of plywood between framing members to increase member strength or other conformity. Another deviation from standard sizing is the introduction of a ledger board of dissimilar size or material to the framing members. Further examples are when joists and/or headers and/or rafters need to be in precise locations in close proximity to each other such that there is inadequate clearance between members to insert and/or fasten separate joist hangers. These are some but not all of the situations where an in-between size or oversize joist hanger is necessarily required but no suitable product is readily available.
The most common solution to the problem of not having a unique size joist hanger is to pay someone to manufacture a custom joist hanger. Purchasing a custom made joist hanger from a fabricator is a time consuming and relatively expensive process. The custom joist hanger must first be designed and then ordered. The fabricator must them form and/or weld a metal piece or pieces. Holes for fasteners must be made in the completed joist hanger. This work is performed manually by a mechanic or by a mechanic operating machinery. The custom made joist hanger must also be delivered to the location where it is needed and then installed. There are some joist hangers such as those made by a steel fabricator that are made from light guage angle steel as opposed to the sheet metal that is commonly used to manufacture mass-produced joist hangers. These heavier guage steel joist hangers require installation with large screws or lag bolts which need pilot holes to be drilled in the framing members for proper installation. The purchaser of the custom joist hanger commonly waits one day or more to get the finished product. The cost of this process substantially exceeds that of a mass-produced joist hanger.
A look at the earlier days of joist hangers reveals in the year 1895 U.S. Pat. No. 537,505 was granted for Van Dorn's joist hanger which is a forerunner of modern joist hangers. Van Dorn's joist hanger is essentially a horizontal shelf or seat supported by opposing vertical flanged side brackets formed as one continuous piece of metal. The supported member is then seated on the horizontal shelf and the opposing side brackets are fastened to the supporting and supported members.
While the essence of Van Dorn's joist hanger has not changed, patents have been granted for varying forms. One such variation is U.S. Pat. No. 4,480,941 November 1984 by Gilb and Commins for the “Double Shear Angled Fastener Sheet Metal Connector”. The innovation of ‘double shear’ applied to a Van Dorn style joist hanger increased the strength and efficiency of the joint held by the improved joist hanger. However neither the Van Dorn design (537,505) nor the Gilb and Commins design (4,480,941) allow the user to vary the joist hanger seat width or utilize the seat as a third fastening bracket to introduce shear strength on the plane of the seat.
Another variation of joist hangers is Turner's “Expandable Joist Hanger” U.S. Pat. No. 5,111,632 May 1992. Turner's patent provides an adjustable seat width joist hanger intending to solve some or all of the problems that are the subject of this application. In all of its described forms Turner's patent provides a non-contiguous unassembled joist hanger that consists of multiple, separate, and distinct metal brackets. These brackets are arranged around the end of a joist in a prescribed fashion and fastened to supported and supporting members. While each individual bracket that makes up Turner's joist hanger is fastened to its respective framing member, the product remains a non-contiguous joist hanger.
By its own definition the Turner joist hanger is slideable and moveable. Its expandability is dependent on the arrangement of individual brackets whose intersection(s) form break-points. The inherent weakness of break-point(s) in the joist hanger leave the Turner disign at a critical disadvantage compared to contiguous joist hangers. This critical disadvantage is manifest as an inability of two or more separate pieces of metal to have the comparable tensile strength of one contiguous piece of similar metal for the purpose of providing a supporting seat or platgorm in a joist hanger application. The ability of a joist hanger seat to carry a load is dependent on the tensile strength of the joist hanger metal. Increasing the tensile strength of the joist hanger increases its resistance to deformity and subsequent failure. The only method known to this applicant to render the Turner joist hanger comparable in tensile strength to a contiguous metal joist hanger is to weld the individual brackets together. This remedy is costly, inefficient, and the quality of the joist hanger is subject to the skills of the welder.
The economic disadvantages of the Turner “Expandable Joist Hanger” are apparent in the amount of effort required to manufacture the individual brackets. To manufacture one joist hanger in each of its 5 different illustrated forms would require 12 unique, non-interchangeable brackets. These 12 brackets must be bent a collective total of 28 times. One of the 12 brackets requires welding. A brief overview of the 5 illustrated forms of Turner's “Expandable Joist Hanger” is as follows:                Slideably Engaged version: This version is the primary embodiment. It is made from 3 brackets requiring a total of 12 bends of which there are 3 different types: 90°, 180°, and offset. This version is the most complicated to manufacture. Contains multiple break-points.        Angularly Adjustable version: This version is made from 3 brackets requiring a total of 2 bends at 90°. The pivot bracket that functions as a seat requires welding. Contains multiple break-points.        Overlay Platform version: This version is made from 2 brackets requiring 5 bends at 90°. One bend is integral to the retention of displaced metal. One bracket requires special slotting to recieve displaced metal from the mating bracket. Contains one break-point.        Adjacent Tongue version: This version is made from 2 brackets requiring 4 bends at 90°. Each bracket requires special slotting to recieve displaced metal from the mating bracket. Contains multiple break-points.        Perpendicular Extension version: This version is made from 2 brackets requiring 5 bends, 4 of which are at 90° and 1 bend is slightly less than 90°. One bracket requires special slotting to recieve the tongue of the mating bracket. Contains one break-point.The complexity and close tolerances between engageable elements, especially apparent in the primary embodiment, are a burden to manufacturing as each of Turner's multiple brackets requires its own tooling and manufacturing procedure. Comparative to this is classic design joist hanger manufacturing which is fast and efficient in that it comprises one bracket with 4 bends at 90° under one tooling and manufacturing procedure.        
Another disadvantage by comparison is time spent on installation. The classic design joist hanger has a simpler and faster installation procedure than the Turner multiple bracket system because no time need be spent on aligning and assembling engageable brackets.
The Turner multiple brackets also present a problem by leaving protruding metal. In the very least, the primary embodiment introduces a safety hazard by leaving a sharp metal corner protruding laterally from each side of the joist hanger. The angularly adjustable version produces two such problems. Sharp metal corners protrude vertically downward below the horizontal plane of the bottom of the joist on each side of the joist hanger. A pivot rod also protrudes laterally from each side of the joist hanger. The overlay platform version leaves a tab of displaced metal protruding below the plane of the bottom of the joist. The adjacent tongue version leaves two problems similar to the angularly adjustable version. Sharp corners are left protruding vertically downward and lateral tongues extend from each side of the joist hanger. The perpendicular extension version requires the deliberate deforming of a protruding part of the bracket that leaves the hazard of an unsecured metal tab. The downward protrusions also present interference regarding interior finishing. Joists are commonly finished with sheetrock and any protrusion into the planar surface, whether large or small, interferes with the sheetrocking procedure.
Further disadvantage is noted in the multiple bracket system itself embodied in all forms of Turner's “Expandable Joist Hanger”. Joist hangers are used primarily by carpenters and mechanics who use vans and trucks to transport and store their wares. Any person familiar with contractor vans and box trucks knows that small objects like metal brackets can become lost, scattered, stepped on, and appropriated for things other than intended use. In this way the Turner multiple bracket system can become a nuisance.
There is no joist hanger known to this applicant that combines the tensile strength of a contiguous joist hanger, the versatility of user determinable size, and the efficiency of cost-effective manufacturing. The Turner multiple bracket system lacks critical strength and production efficiency. Classic joist hanger designs offer superior strength and production efficiency. Classic joist hanger designs however fail to provide a means by which to vary joist hanger width, which is the subject of the present application.